The present invention relates to a sensor system including a large number of sensor units (such as optical fiber photoelectric sensor units, proximate sensors or ultrasonic sensors) mounted closely one next to another typically on a DIN rail, and in particular to a sensor system which simplifies the setting operation and monitoring of settings of such sensor units by enabling a bi-directional data communication between the adjacent sensor units in the manner of a bucket brigade.
Sensor systems including a large number of optical fiber photoelectric sensor units mounted closely one next to another on a DIN rail are conventionally known. The outer face of each of such sensor units is provided with a digital display unit consisting of seven-segment display devices and a keypad which may comprise function keys and increment keys. Such a display unit and keypad are used for adjusting the light receiving sensitivity and threshold level when installing the sensor.
The photoelectric sensor units of this type are given with a higher and higher functionality so that the setting items are increased in number and are each increased in complexity. The increasing demand for space-saving and compact design has resulted in extremely small housings for such photoelectric sensor units, and the keypad and display unit particularly suffer from the impact of the compact design.
Therefore, the display unit is required to be very small, and the number of the setting keys are limited in both size and number. This has increased the difficulty in the setting and adjusting operation. In particular, as the number of sensor units increases to 16, 32 and so forth, the setting and adjusting of each key becomes progressively difficult and time-consuming.
In view of such problems of the prior art, a primary object of the present invention is to provide a sensor system which simplifies the setting and adjustment operation for the sensor units.
Another object of the present invention is to provide a sensor system which simplifies the setting and adjustment operation for the sensor units without requiring any substantial changes to the existing structure of the overall system or the shape of the individual sensor units.
Yet another object of the present invention is to provide a sensor unit which simplifies the setting and adjustment operation for the sensor unit.
Yet another object of the present invention is to provide a mobile console which simplifies the setting and adjustment operation for the sensor units.
Yet another object of the present invention is to provide a bus unit which allows the setting and adjustment operation for the sensor units from a programmable controller, personal computer or the like connected to a field bus.
Other objects and advantages of the present invention will become obvious for a person skill in the art from the following description.
The sensor system of the present invention comprises a plurality of sensor units which are adapted to be placed closely one next to another and each assigned with an individual address, and a mobile console which is adapted to be connected to at least one of the sensor units.
As can be readily appreciated by a person skilled in the art, the xe2x80x9csensor unitxe2x80x9d may comprise any sensing means having a desired sensing capability. The sensing means may consist of optical fiber photoelectric sensor units, proximate sensors and ultrasonic sensors. If the sensor unit consists of an optical fiber photoelectric sensor, the sensing means comprises light emitting means (including both hardware and software), and light receiving means (including both hardware and software). The output signal from the sensing means may not necessarily consist of a binary output (switching output) but may also consist of an analog or digital value without being converted into a binary signal. In view of the fact that they are arranged closely one next to another, the sensor units would typically consist of sensors having separate sensor heads such as optical fiber photoelectric sensors.
Being xe2x80x9cadapted to be placed closely one next to anotherxe2x80x9d includes mounting the sensor units closely one next to another on a DIN rail. However, it is also possible to use other mounting arrangements.
Being xe2x80x9cassigned with an individual addressxe2x80x9d may include making each sensor unit identify a particular address from the relation with the adjacent sensor units according to a free allocation scheme as well as the assigning of a fixed address by using a DIP switch.
According to a preferred embodiment of the present invention, each of the sensor units forwards a handshake signal to the adjacent sensor units. From the response to the handshake signal, each sensor unit can determined if it is at the right or left terminal end or at an intermediate position, and the sensor unit at a terminal end is identified as a master unit and the remaining units as slave units, and addresses are assigned to them accordingly.
The xe2x80x9cmobile consolexe2x80x9d means any portable console (console board). More specifically, the mobile console is at least provided with functions to enter data and read data, and to display the data.
xe2x80x9cAt least one ofxe2x80x9d means that a connection can be made to one or more of the sensor units which are arranged in a series, and it may not necessarily be located at a terminal end, but may also be located in a middle of the series. The xe2x80x9cconnectionxe2x80x9d as used herein means any connection which allows communication, and may consist of wire connection using electric cables and wireless connection using radio wave, light such as infrared light, and so on.
Each of the sensor units may comprise a connector means on each side for allowing communication with a corresponding one of the adjacent sensor units and data relaying means for transmitting data received from one of the adjacent sensor units via the corresponding connector means to the other adjacent sensor unit via the other connector means. Thereby, the bi-directional transfer of data in the manner of a bucket brigade from the mobile console to the sensor units and from the sensor units to the mobile console is enabled.
Comprising xe2x80x9ca connector means on each sidexe2x80x9d means that each sensor is provided with two connector means corresponding to the adjacent sensor units on either side. It means that the sensor units are all connected in a series, and it is distinct from the arrangement in which the I/O units of a programmable logic controller or the like are connected in a mutually parallel relationship with respect to a system bus. However, the sensor unit which is designed to be attached to a terminal end of a sensor unit array may be provided with only one connector means because it is not required to communicate with both of the adjacent sensor units. The xe2x80x9cconnector meansxe2x80x9d as used herein means any connector which is capable of signal transmission and reception, and may include a contact-type electric connector which establishes an electric connection by the contact of a plug and receptacle, and a contact-less connector which exchanges signals by using light (infrared light).
The xe2x80x9cdata relaying meansxe2x80x9d as used herein means both the means which relays data unconditionally and the means which relays data only if it meets a certain condition. A person skilled in the art would select either one of them according to the particular need. If the unconditional data relay means is selected, the execution of the process would be simplified because of the elimination of the need to analyze the condition, but the downstream sensors would be burdened by the data relaying action which may not be necessary. On the other hand, the conditional data relay means is selected, the downstream sensors would not be burdened by the data relaying action which may not be necessary if the data is accompanied with a condition that xe2x80x9cif the data is not intended only for the particular sensor unitxe2x80x9d, but the execution of the process would cause a complication because of the need to analyze the condition. The xe2x80x9cdownstreamxe2x80x9d as used herein means the direction toward the position which is the last to receive data, and may be in either physical direction depending on the direction of data transfer.
xe2x80x9cIf the received setting data is not intended only for the particular sensor unitxe2x80x9d includes the case where the data is intended for another sensor unit as well as the cases where the data is intended for both the particular sensor unit and another sensor unit, or for all of the sensor units.
When the data is relayed between adjacent senor units in the manner of xe2x80x9ca bucket brigadexe2x80x9d according to the present invention, if the arrived data is intended for all of the sensor units, the particular sensor unit has to execute the process of transferring the data to the adjacent sensor unit in addition to executing the process for the particular sensor itself. Associating each transmission data to all of the sensor units can be accomplished in a number of different ways. For instance, the transmission data may be attached with a code corresponding to a wildcard. Alternatively, the transmission data attached with no code may be assumed as being intended for all of the sensor units, or the transmission data may be attached with the addresses of all of the sensor units.
According to a preferred embodiment of the present invention, the sensor unit comprises monitoring data transmitting means for transmitting monitoring data intended for the mobile console to the adjacent sensor unit. The mobile console also comprises monitoring data displaying means for displaying monitoring data received from one of the sensor units.
The xe2x80x9cmonitoring data transmission meansxe2x80x9d as used herein may mean both the means for transmitting monitoring data spontaneously according to a timing determined by a timing signal which is forwarded from a timer or forwarded sequentially from the adjacent sensor unit, and the means for transmitting monitoring data passively in response to a monitoring command forwarded from the mobile console or the like.
Thereby, the state of each sensor unit (such as the set sensitivity level, detected value, and so forth) can be monitored from the mobile console according to the monitoring data relayed between the sensor units in the manner of a bucket brigade.
According to another preferred embodiment of the present invention, the mobile console comprises setting data transmission means for transmitting setting data to a designated sensor unit via one of the sensor units. Each sensor unit comprises data setting means for conducting a data setting action according to setting data if the data received from the adjacent sensor unit is intended for the particular sensor unit and consists of setting data transmitted from the mobile console.
The xe2x80x9cdesignated sensor unitxe2x80x9d as used herein may mean a single sensor unit, two or more sensor units or all of the sensor units which is or are designated. When designating a particular single sensor unit, the setting data of the particular sensor unit would typically contain an address corresponding to the target sensor unit. When a plurality of sensor units are to be designated, different setting data would be forwarded to the designated sensors, and the data for each designated sensor would contain an address corresponding to the target sensor unit. All of the sensor units can be designated in the same manner as designating a plurality of sensor units. It may include the case where a wildcard designating all of the sensor units is attached to a common setting data item.
The data xe2x80x9cintended for the particular sensor unitxe2x80x9d includes not only the data only for the particular sensor unit, but also the data intended for the particular sensor unit and another sensor unit, or all of the sensor units.
The xe2x80x9cdata setting meansxe2x80x9d of the sensor unit may not necessarily execute a setting action on the condition of reading a data setting command. In other words, it may include those which spontaneously execute a setting action unconditionally according to the setting data if the data received from the adjacent sensor unit is intended for the particular sensor unit and consists of data transmitted from the mobile console.
According to the above described structure, because the data setting action is executed according to the setting data transmitted from the mobile console in the manner of a bucket brigade, the setting of the sensitivity and functions can be conducted from the mobile console, and it is a significant improvement from the conventional arrangement which required each sensor unit to be set by a key operation.
According to yet another preferred embodiment of the present invention, the mobile console comprises command data transmitting means for transmitting data containing a command intended for a designated sensor unit to one of the sensor units. Each sensor unit comprises command data executing means for conducting a certain action according to a command if the data received from the adjacent sensor unit is intended for the particular sensor unit and contains such a command.
The data xe2x80x9cintended for the particular sensor unitxe2x80x9d includes not only the data only for the particular sensor unit, but also the data intended for the particular sensor and another sensor, or all of the sensor units.
The xe2x80x9ccommandxe2x80x9d used herein may comprise what is broadly defined as a command. Each sensor unit is provided with a capability to execute a process of analyzing the command and conducting a corresponding action. The command may come in a wide variety depending on the kind of the sensor unit (photoelectric sensor, proximate sensor, ultrasonic sensor and so forth), and the functions it performs.
Thereby, the action of each sensor unit can be conducted according to a command issued from the mobile console and passed on from one sensor unit to another in the manner of a bucket brigade.
In the case of a sensor system which allows the action of each sensor unit to be conducted according to a command issued from the mobile console according to a preferred embodiment of the present invention, the command may include various commands.
According to a preferred embodiment of the present invention, the command consists of a monitor command which is associated with the action to read the data of a monitor item designated by the monitor command, and return the data to the mobile console as monitor data.
According to this structure, the state of each sensor unit can be monitored from the mobile console. Each sensor unit may not provide an adequate space for the keypad and display unit because of the compact design for its housing, but the mobile console does not suffer from such a restriction. Therefore, a favorable handling and visibility can be achieved.
According to a preferred embodiment of the present invention, the command consists of a data setting command which is associated with the action to write the data attached to the data setting command into a setting item designated by the data setting command.
According to this structure, the state of each sensor unit can be set by a operation of the mobile console, and the handling can be improved for the reasons mentioned above.
According to a preferred embodiment of the present invention, the command consists of a disable command which is associated with the action to disable the manipulation of a key of the sensor unit corresponding to a function designated by the disable command.
Thus, by using such a disable command, a security is placed on a function which is not desired to be changed by the operator or other personnel on the site.
According to a preferred embodiment of the present invention, the command consists of a concealed function executing command which allows a concealed function to be executed, the concealed function being unable to be invoked by a key operation from the sensor unit.
By thus concealing the function which should not be entrusted to personnel other than the designer or administrator, the security of the system can be ensured.
The sensor system according to a different embodiment of the present invention comprises a plurality of sensor units which are adapted to be placed closely one next to another and each assigned with an individual address, and a bus unit which is adapted to be connected to at least one of the sensor units.
Each of the sensor units comprises a connector means each side for allowing communication with a corresponding one of the adjacent sensor units; and data relaying means for transmitting data received from one of the adjacent sensor units via the corresponding connector means to the other adjacent sensor unit via the other connector means.
The bus unit comprises protocol conversion means for converting a communication protocol between sensor unit communication system and field bus communication system which is connected to equipment such as a programmable controller and personal computer.
Thus, it permits a bi-directional data communication between the equipment such as a programmable controller and personal computer on the field bus and the sensor unit.
According to this structure, the data such as a detected value and switching output which otherwise issues from each individual sensor unit can be wholly obtained from the side of the bus unit, and forwarded to the programmable logic controller so that the output line extending from each individual sensor unit can be omitted. This contributes to the simplification of wiring requirement.
According to a preferred embodiment of the present invention, each sensor unit comprises command executing means for executing an action associated with the command if the received command data is intended for the particular sensor unit and contains a command.
Thereby, the action of each sensor unit can be executed according to a command from equipment on the field bus. In other words, because a programmable controller (PLC), a FA (factory automation) personal computer (FA PC) and so on can be connected to the field bus, it is possible to invoke the desired function of each sensor unit by issuing commands such as monitor commands and data setting commands from such equipment.
To realize such a sensor system, sensor units having a certain structure is used. This sensor unit comprises a connector means on each side for allowing communication with a corresponding one of adjacent sensor units; data relaying means for relaying data received from one of the adjacent sensor units via one of the connector means to the other adjacent sensor unit via the other connector means; and command executing means for receiving data from an adjacent one of the sensor units via one of the connector means, and executing a command if the received data is intended for the particular sensor unit, and when the received data contains the command.
In the case of the sensor units also, it is preferable to use a number of basic commands. According to a preferred embodiment of the present invention, the command consists of a monitor command which is associated with the action to read the data of a monitor item designated by the monitor command, and return the data to the mobile console as monitor data.
According to a preferred embodiment of the present invention, the command consists of a data setting command which is associated with the action to write the data attached to the data setting command into a setting item designated by the data setting command.
According to a preferred embodiment of the present invention, the command consists of a disable command which is associated with the action to disable the manipulation of a key of the sensor unit corresponding to a function designated by the disable command.
According to a preferred embodiment of the present invention, the command consists of a concealed function executing command which allows a concealed function to be executed, the concealed function being unable to be invoked by a key operation from the sensor unit.
In the sensor system of the present invention described above, a mobile console having a certain structure is used. According to a preferred embodiment of the present invention, the mobile console is adapted to be connected to one of a plurality of sensor units each adapted for a bi-directional communication with adjacent sensor units and a relaying function for data that is not intended for the particular sensor unit.
According to a preferred embodiment of the present invention, the mobile console may comprise command means for entering various commands; display means for displaying various items of data; monitor command transmitting means for transmitting a monitor command to a designated sensor unit in response to a command entered from the command means; and monitoring data display means for displaying on the display means monitoring data that is returned from the designated sensor unit in response to the transmission of the monitor command.
According to a preferred embodiment of the present invention, the mobile console comprises command means for entering various commands; display means for displaying various items of data; and setting data transmission means for transmitting setting data to a designated sensor unit in response to a command from the command means.
According to a preferred embodiment of the present invention, the mobile console comprises command means for entering various commands; display means for displaying various items of data; and disable command transmission means for transmitting a disable command to a designated sensor unit in response to a command from the command means.
According to a preferred embodiment of the present invention, the mobile console comprises command means for entering various commands; display means for displaying various items of data; and concealed function executing command transmission means for transmitting a concealed function executing command to a designated sensor unit in response to a command from the command means.
According to the sensor system of the present invention, data transfer can be accomplished by connecting thereto any control unit other than the mobile console and bus unit mentioned above. This is so because the sensor unit array is provided with the function to accomplish a bi-directional data transfer in the manner of a bucket brigade.
Essentially, the sensor system of the present invention comprises a plurality of sensor units which are adapted to be placed closely one next to another and each assigned with an individual address, and a mobile console which is adapted to be connected to at least one of the sensor units, each of the sensor units comprising: a connector means on each side for allowing communication with a corresponding one of the adjacent sensor units; and data relaying means for relaying data received from one of the adjacent sensor units via one of the connector means to the other adjacent sensor unit via the other connector means so as to permit a bi-directional data communication from the mobile console to the sensor units or from the sensor units to the mobile console in the manner of a bucket brigade.
Essentially, the bus unit of the present invention is adapted to be connected to one of a plurality of sensor units each adapted for a bi-directional communication with adjacent sensor units and a data relaying function comprising: protocol conversion means for converting a communication protocol between sensor unit communication means and field bus communication means which is connected to equipment such as a programmable controller and personal computer, so as to permit a bi-directional data communication between the equipment such as a programmable controller and personal computer on a field bus and the sensor unit.
In connection with the sensor system, sensor unit and mobile console which are described above, the sensor units preferably comprise optical fiber type photoelectric sensor units.
The connector means may comprise a light emitting element and a light receiving element so as to allow transmitting and receiving light signals.
By using such an optical connector, the side faces of the unit housing may be given with a flat surface, as opposed to the case using a male and female connector. This contributes to the improvement in the immunity against electromagnetic interferences and the elimination of poor contact problems.
One of the advantages of the mobile console of the present invention is found in the fact that although the sensor unit array is typically placed in a narrow and poorly accessible space in a control console or the like, because the mobile console may be placed in a highly accessible place remotely from the sensor array, the monitoring or other work related with the sensor system can be facilitated.
This advantages owes to the data collecting function of the mobile console based on communication, and does not rely on the use of the bucket brigade scheme or the common transmission line (bus) scheme. In this regard, the mobile console of the present invention can be characterized as given in the following.
The mobile console of the present invention is provided commonly for a number of sensor units arranged one next to another and each provided with a communication function. Being xe2x80x9cprovided commonlyxe2x80x9d means that it is not provided for each of the sensor units. The data communication between the sensor units may be based on the bucket brigade scheme or the common transmission line (bus) scheme.
The mobile console is provided with command means; display means; and control means for taking out data on each designated sensor unit from the sensor unit by communication according to a command entered from the command means, and displaying the data on the display means. The target for the communication by the mobile console is not limited to the sensor units in the array. It is also possible to provide an infrared communication function in each of the sensor units so that the mobile console may communicate directly with them, without the intervention of any other sensor units, to allow the data to be collected individually.
According to the mobile console of the present invention, the communication with the sensor units may be conducted via a single sensor unit or a common transmission line. In other words, it is possible to relay the data received by one of the sensor units to an adjacent sensor unit in the manner of a bucket brigade or by forwarding the data to a common transmission line.
According to the mobile console of the present invention, the communication with the single sensor unit or common transmission line is conducted via wire transmission using an electric cord, or wireless transmission using infrared light, radio wave and ultrasonic radiation so as to allow the data of the sensor units to be monitored remotely. According to such an arrangement, the mobile console may be easily separated from the sensor unit array so that the data of the sensor units can be easily monitored and adjusted remotely.
According to the mobile console of the present invention, the data of the sensor units comprises a detected analog value or a threshold level for a binary. As can be readily appreciated, the data may also comprise data of any other kind.
The external appearance of the mobile console of the present invention may characterized by a housing provided with a keypad serving as the command means and a display unit serving as the display means, the housing being so dimensioned and configured as to permit the keypad to be manipulated with one hand while holding the housing with the other hand. This obviously enhances the handling of the mobile console.